I would like to tell you about a prescription drug I am taking with PLEASANT SIDE EFFECTS. It is a brand name drug called Entex LA. [Erowid Note: Entex LA is a time release forumula containing guaifenesin, phenylephrine, and phenylpropanolamine.
Phenylephrine
Limited data
Limited data
Sparse data. Doses and effects may be unreliable or untested.
- 1 source
- partial dose data
- duration data present
- PubChem toxicity data
- dose data not in PW/TripSit (unverifiable)
Limited data
Sparse data. Doses and effects may be unreliable or untested.
- 1 source
- partial dose data
- duration data present
- PubChem toxicity data
- dose data not in PW/TripSit (unverifiable)
Aliases: Mesaton, Mezaton, Mydfrin, Isophrin, Visadron
Summary
Phenylephrine is primarily used as a decongestant, vasopressor, and mydriatic agent. It has poor oral bioavailability (~38%) due to extensive first-pass metabolism. The FDA has questioned its efficacy as an oral decongestant, with studies showing it performs no better than placebo at standard 10 mg doses.
Dose Information
| ROA | Light | Common | Strong | Heavy |
|---|---|---|---|---|
| Nasal | 0.25-0.5mg | - | - | - |
| Ophthalmic | 1-2.5% | - | - | - |
Light
Common
Strong
Heavy
Onset, Duration & After-effects
| ROA | Onset | Comeup | Peak | Offset |
|---|---|---|---|---|
| Oral | 15-30 min | 30-60 min | 1-2 hrs | 1-2 hrs |
| Intravenous | - | 1-2 min | 5 min | 10-15 min |
| Nasal | 5-10 min | 10-20 min | 15-30 min | 1-2 hrs |
| Ophthalmic | 1-5 min | - | 30-60 min | 2-4 hrs |
Effect Profile
4 reportsScores (1–10) curated from multiple sources:
- Effect keyword matching from PsychonautWiki catalog
- Weighted by importance: core (×3), major (×2), minor (×1)
Stimulant
5.8
Strong
6/10
Strong anxiety/jitters with moderate euphoria, focus, and stimulation
Stimulation / Energy
×3
6
stimulation
wakefulness
alertness enhancement
Euphoria / Mood Lift
×2
7
euphoria
cognitive euphoria
motivation enhancement
Focus / Productivity
×2
7
focus enhancement
motivation enhancement
thought acceleration
Anxiety / Jitters
×1
10
anxiety
restlessness
increased heart rate
vasoconstriction
Based on reports from:
Tolerance
Build-up
develops rapidly after a single use (serotonergic psychedelic)
Reset
7–14 days for baseline
Tolerance Decay
Full tolerance
4d
Half tolerance
7d
Baseline
~14d
Acute tolerance: develops within a single session — the reset numbers above apply after sustained heavy use, not after one binge. Within-session tachyphylaxis usually resets largely overnight.
Tolerance data primarily reflect intranasal, continuous daily use leading to rhinitis medicamentosa (tachyphylaxis/rebound). Onset of clinically relevant tolerance and rebound has been reported as early as ~3 days; symptoms generally improve within days to a few weeks after cessation with supportive care. Systemic tolerance patterns are less defined. Data quality is limited and variably generalizable.
Cross-Tolerances
Effects
Positive
- Nasal decongestion
- Stimulation
Negative
- Vasoconstriction
- Increased blood pressure
- Pupil dilation
- Headache
- Restlessness
- Increased heart rate
- Insomnia
- Reflex bradycardia
Positive
- Alertness enhancement
- Euphoria
- Wakefulness
- Cognitive euphoria
- Motivation enhancement
- Focus enhancement
Negative
- Anxiety
- Talkativeness
- Time distortion
- Thought acceleration
Positive
- Increased music appreciation
- Tactile enhancement
- Increased libido
- Color enhancement
Negative
- Light sensitivity
- Appetite suppression
- Dehydration
- Disinhibition
- Drifting
- Dulled perception
Community Trip Reports
Anecdotal first-person accounts from Reddit, Erowid, and Bluelight. Click a source to expand. Reports are harm-reduction context, not medical guidance.
Erowid 3 reports 1 positive 2 neutral visit
I was sick with a cold, so I bought some nasal decongestion spray. This was the one with phenylephrine in it. I had experience with the one with oxymetazoline hcl, so I thought I would try phenylephrine. Here is what I did.
Previous experiences; DXM, DHP, Cannabis, Alcohol, Nitrous, Concerta, Vyvanse, Pseudoephedrine I'll caveat by saying this was the generic, CVS-brand Sudafed that cost about 5 bucks for 36 caplets. Taking 5 10-mg caplets, the effects peaks at a sort of 'wide awake' state 2 hours after consuming, with a nice comedown.
Pill Identifiers
4
known pill identifiers on record — view imprints, colors, shapes, and images
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Phenylephrine's nerd page
Pharmacology, chemical data, effect profiles, and more
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Helpful Links
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